The overall goal of this project is to increase our understanding of the HLA-linked susceptibility to autoimmune diseases. A variety of autoimmune disorders have been associated with serologically defined variants at the HLA class ll loci. Recently, molecular analyses of class II polymorphisms have revealed the heterogeneity within these serotypes and suggested that structural variation in the class ll products of HLA-DR and -DQ may confer disease susceptibility. The structures of the DPalpha and DPbeta genes as well as their role in disease susceptibility, however, have not yet been thoroughly investigated. We propose to use the polymerase chain reaction (PCR) method to amplify the DPalpha and DPbeta genes from a variety of individuals. Characterization of the alleles will initially be done by sequence analysis. Based on these sequences, non-isotopic oligonucleotide probes will be synthesized and used in a dot blot format to rapidly screen a large number of individuals from different ethnic groups to ascertain allele frequencies and identify new alleles. The role of DP in disease susceptibility will be investigated using the same dot blot format on patient populations as well as the appropriate controls. The autoimmune diseases investigated will include juvenile rheumatoid arthritis, adult rheumatoid arthritis, multiple sclerosis, celiac disease, myasthenia gravis, IDDM and Pemphigus vulgaris. All samples will also be DNA-typed for HLA-DR and -DQ since, based on our previous work, disease susceptibility appears most highly associated with specific combinations of class ll alleles. In order to determine whether a particular disease-associated DP allele actually contributes to susceptibility independent of other HLA-D region alleles or whether it simply "marks" an extended "disease" haplotype we will need to determine whether any of the DP alleles are in linkage disequilibrium with a particular HLA haplotype. We will therefore examine the association of DR, DQ, and DP types in both family studies and in homozygous typing cells. The recombination rate between DP and DR/DQ will also be measured by utilizing the ability of PCR to co-amplify two genes, here DPbeta and DQalpha, from single sperm. The role of DP polymorphism in graft vs. host disease will be determined by DP-typing 200 bone marrow recipients and their apparently "HLA"-matched donor sibs, to determine whether differences at the DP locus correlate with occurrence of graft vs. host disease. Finally, we will look at the evolution of polymorphism at the DP locus by characterizing its allelic polymorphism in other primates. These studies will not only contribute to our understanding of the structure of the DP molecule and its role in disease susceptibility but also to its importance in the biology of tissue transplantation.